Various fasteners have been used on inexpensive or disposable garments such as diapers, including lengths of pressure-sensitive adhesive coated tape, snaps, and hook and loop fasteners.
Of these, lengths of pressure-sensitive adhesive coated tape are presently most widely used as the fasteners for disposable diapers, however the presence of relatively small amounts of contaminants such as talcum powder or baby oil either on the pressure-sensitive adhesive or on the portion of the garment to which the pressure-sensitive adhesive is to be adhered by the user can reduce the reliability of the fastener.
The use of hook and loop fasteners on inexpensive or disposable garments such as diapers substantially overcomes this problem of reduced fastener reliability due to contaminants such as talcum powder or baby oil, however, many hook and loop fasteners are too expensive to be economically used on disposable diapers, particularly since the loop portion must be very large to provide a variety of fastening locations for the hook portion to fit various sizes of babies to which the diapers may be attached. Thus, inexpensive portions for hook and loop fasteners are being developed that can securely close the diaper and allow a limited number (e.g., 10) openings and closings of the fastener without seriously degrading it, and are sufficiently inexpensive that they can economically be used on a disposable diaper or similar garment. Included in such development as is described in U.S. Pat. application No. 126,746 filed Nov. 30, 1987, are loop fastener portions having loops projecting from one surface that are formed by stitching through a backing, sonically welding portions of fibers to one face of a backing layer, or by providing a nonwoven fibrous layer that provides such loops. Typically, such inexpensive loop fastener portions provide per unit area fewer, smaller loops with less height compared to most commercially available woven or knitted loop fastener portions (e.g., the loop fastener portion commercially available as Style No. 19149 nylon 66 loop material from Guilford Mills, Inc., Greensboro, NC). Thus, the level of engagement with such inexpensive loop fastener portions by commercially available hook fastener portions, whether of the type having monofilament hooks projecting from a woven or knit backing formed by cutting monofilament loops along one side (e.g., see U.S. Pat. No. 3,027,566) or of the type having monofilament stems with mushroom shaped heads on their distal ends and projecting from a backing that may be woven, knit or a unitary layer in which the stems are embedded (e.g., see U.S. Pat. Nos. 3,270,408 and 4,290,832), or of the type having unitary backings and projecting hook members molded together or formed by extrusion techniques, is not as good as the level of engagement those commercially available hook fastener portions make with the more costly woven or knitted loop fastener portions described above. A hook fastener portion of the type having projecting monofilament or molded stems with mushroom shaped heads on their distal ends will not make good engagement with such inexpensive loop fastener portions because for good engagement with such a mushroom shaped head a loop must be sufficiently long so that it can wrap almost completely around the stem under the head. Hook fastener portions of types having monofilament hooks projecting from a woven or knit backing formed by cutting monofilament loops along one side can engage with such inexpensive loop fastener portions better than stems with mushroom shaped heads, however the monofilament hooks are so flexible that they do not provide the desired level of shear strength when engaged with such inexpensive loop fastener portions. Hook fastener portions of the type having unitary backings and projecting hook members molded together or formed by extrusion techniques (which are the least expensive and thus from that standpoint are most suitable for use on disposable garments such as diapers) have greater shear strength than the monofilament hooks, but are too large to easily enter between the random loops of nonwoven inexpensive loop fastener portions Additionally, known hook fastener portions having unitary backings and projecting hook members made by molding or extrusion techniques are rigid as well as being quite large and therefore have a very abrasive feel when their projecting hook members are pressed against a person's skin so that they could cause concern among mothers or other users that inadvertent contact between such projecting hook members and the skin of a person, such as a baby, could cause discomfort or injury.